Polymerization catalyst



United States Patent 3,281,375 POLYMERIZATION CATALYST Edwin J. Vandenberg, Wilmington, DeL, assignor to Hercnles Incorporated, Wilmington, Del., a corporation of Delaware No Drawing. Original application Apr. 7, 1955, Ser. No. 500,041, now Patent No. 3,058,963, dated Oct. 16, 1962. Divided and this application Oct. 9, 1961, Ser. No. 143,553

3 Claims. (41]. 252-429) This application is a division of my application Serial No. 500,041, filed April 7, 1955, and now U.S. Patent No. 3,058,963.

This invention relates to an improved process for polymerizing olefins alone or in admixture with other olefins whereby it is possible to carry out the polymerization at atmospheric or only slightly elevated pressures and at relatively low temperatures and obtain polymers and copolymers exhibiting unusual properties.

In Belgian Patents Nos. 533,362, 534,792 and 534,888 of K. Ziegler et al. there is described a new process of polymerizing ethylene to a high molecular weight polyethylene under relatively mild conditions of temperature and pressure by using as the catalyst for the polymerization a mixture of a compound of a metal of Groups IV-B, V-B, VI-B or VIII of the periodic table, or manganese, in combination with an organometallic compound of an alkali metal, alkaline earth metal, zinc, earth metal (especially aluminum), or rare earth metal. The usual procedure for carrying out such a process is to mix two catalyst components in a hydrocarbon solvent and then pass ethylene into the catalyst mixture at atmospheric or slightly elevated pressure and at room temperature or moderately elevated temperatures. It has been suggested that a reduction of the tetravalent titanium or other transition metal occurs on admixture with the organo-aluminum compound to produce a mixture of lower valence compounds, but the mechanics of the reaction are not known. That a reaction has taken place is generally evidenced by the formation of a colored, usually brown to black, precipitate on admixture of the two reactants.

Now, in accordance with this invention, it has been found that greatly improved polymerization results may be obtained by using a two-component catalyst system comprising (1) the hydrocarbon-insoluble reaction prod uct obtained in the above-mentioned Ziegler catalyst preparation and separated from the hydrocarbon-soluble phase and (2) an organometallic compound of a metal from the group of alkali metals, alkaline earth metals, zinc, earth metals, and rare earth metals. By utilizing this twocomponent catalyst it is possible to polymerize ethylenically unsaturated hydrocarbons under mild conditions of temperature and pressure more effectively and realize many other advantages, such as improved rate of polymerization and space-time yields, use of lower catalyst concentrations, etc. Of particular importance, especially for the more readily polymerized olefins such as ethylene and propylene, is the fact that under any given set of conditions the molecular weight of the polymer may be more effectively controlled.

The hydrocarbon-insoluble reaction product catalyst component used as one of the catalyst components in the process of this invention is readily prepared by simply mixing the defined metal compound of the designated groups of the periodic table with the organometallic compound of the selected metal and then separating the hydrocarbon-insoluble component that is formed. As already pointed out, the transition metal compound may be a compound of any metal of Groups IV-B, V-B, VI-B or VIII of the periodic table, i.e., titanium, zirconium, hafniurn, chorium, vanadium, columbium, tantalum, chromium,

"ice

molybdenum, tungsten, uranium, iron, cobalt, nickel, etc., or manganese. The compound may be an inorganic salt such as a halide, oxyhalide, etc., or an organic salt or complex such as an acetylacetonate, etc. Exemplary of such compounds are titanium and zirconium tetrachloride, manganous chloride, nickelous chloride, ferrous chloride, ferric chloride, tetrabutyl titanate, zirconium acetylacetonate, vanadium oxy acetylacetonate, chromium acetylacetonate, etc. The organometallic compound that is reacted with one of the transition metal compoundsor mixtures thereof may be any organo compound of an alkali metal, alkaline earth metal, zinc, earth metal, or rare earth metal, as for example, alkali metal alkyls or aryls such as butyllithium, amylsodium, phenylsodium, etc., dimethylmagnesium, diethylmagnesium, diethylzinc, butylmagnesium chloride, phenylmagnesium bromide, triethylaluminum, tripropylaluminum, triisobutylaluminum, trioctylaluminum, tridodecylaluminum, dimethyl aluminum chloride, diethylaluminum bromide, diethylaluminum chloride, ethylaluminum dichloride, the equimolar mixture of the latter two known as aluminum sesquichloride, dipropylaluminum fluoride, diisobutylaluminum fluoride, diethylalurninum hydride, ethylaluminum dihydride, diisobutylaluminum hydride, etc., and complexes of such organometallic compounds, as for example, sodium aluminum tetraethyl, lithium aluminum tetraoctyl, etc.

The reaction between the transition metal compound and the organometallic compound to provide the hydrocarbon-insoluble component of my improved catalyst may be carried out by mixing the two compounds in an inert diluent, as for example, aliphatic hydrocarbons such as hexane, heptane, etc., cycloaliphatic hydrocarbons such as cyclohexane or aromatic hydrocarbons such as benzene, toluene, xylene, etc., halogenated aromatic hydrocarbons such as chlorobenzenes, chloronaphthalenes, etc., or any mixture of such inert diluents. Any concentration of the two reagents may be used that is convenient. Another method that may be used in preparing this hydrocarboninsoluble catalyst component is to simply mix the two reagents, i.e., without the use of a diluent. In this case, after the reaction is substantially complete, the hydrocarbon-insoluble reaction product will be isolated by extraction of the mixture with an inert solvent. The reaction of the two compounds may be carried out at any temperature and will generally be determined by the solvent, if used, the activity of the reactants, etc. For example, some metal alkyls might react at Dry Ice temperatures whereas others would require elevated temperatures. Usually the reaction is conveniently carried out at room temperature or slightly elevated temperatures, but a temperature of from about 50 C. to about 150 C. could be used.

In preparing the hydrocarbon-insoluble component of my catalyst the molar ratio of the two reactants may likewise be varied over a wide range. It is believed that a reduction of the transition metal compound from the higher valence state of the transition metal to one or more lower valence states takes place. Hence there should be used an amount of the organometallic compound that will produce the desired amount of reduction. Thus, larger ratios of organometallic compound to the transition metal compound are required for alkali metal alkyls than for a trialkylaluminum and in the same way, more of an alkylaluminum dihalide than a dialkylaluminum monohalide. In general, the molar ratio of organometallic compound to transition metal compound will be from about 0.1:1 to :1 and more usually will be from about 0.311 to 10:1.

That a reaction takes place between the organometallic compound and the transition metal compound is readily apparent in those cases where both reagents are soluble in the hydrocarbon diluent inasmuch as an insoluble precipitate will form, as for example, in the case of the reaction of titanium tetrachloride with any of the aluminum alkyls, etc., or the reaction of such compounds as zirconium acetylacetonate with any of the aluminum alkyls. It is this insoluble precipitate which is used as one of the reaction components in accordance with this invention. It should be pointed out that in some cases the transition metal compound used as the starting reactant may not be soluble to any appreciable degree, as for example, zirconium tetrachloride, in the inert diluent. However, the reduction by-products are soluble and thus the insoluble product that remains is the desired hydrocarboninsoluble reaction product catalyst component. In a few cases the reaction of the transition metal compound with the organometallic compound may not produce an insoluble precipitate, as for example, when tetrabutyl tit-anate is reacted with triethylaluminum in n-heptane. By using an aluminum alkyl halide such as diethylaluminum chloride, a precipitate is readily formed. It is also possible to vary the diluent used for carrying out the reac' tion and obtain the desired precipitate.

These hydrocarbon-insoluble catalyst components may be separated from the reaction mixture as soon as the reaction is substantially complete and then used in the polymerization. If an inert diluent is used in carrying out the reaction, the insoluble reaction product may be separated from the diluent and the soluble reaction byproducts by simply allowing the mixture to settle, centrifuging, etc., and decanting the supernatant liquid, or they may be separated by filtration, etc. If the reaction was carried out in the absence of a diluent, the hydrocarbon-insoluble reaction product may be separated by extracting the reaction mixture with an inert hydrocarbon diluent so as to remove the hydrocarbon-soluble byproducts. However, the activity of the hydrocarbon-insoluble reaction product catalyst component is in some cases further enhanced by allowing it to age before use. Preferably the aging will be carried out prior to separating the insoluble reaction product from the reaction mixture although it may be done after it has been separated. The aging may be carried out by allowing the reaction mixture or a suspension of the insoluble catalyst component in an inert hydrocarbon diluent to stand at room temperature or thereabouts for anywhere from a few hours to weeks, or it may be greatly speeded up by carrying out the aging at elevated temperatures up to a temperature of about 100 C. or above. In many cases, and particularly those hydrocarbon-insoluble reaction products prepared from aluminum sesquihalides or alkylaluminum dihalides, it is desirable to Wash this insoluble precipitate, after it has been separated, one or more times with the inert hydrocarbon solvent so as to remove substantially all of the soluble by-products that are formed in the reaction or other hydrocarbon-soluble material. This washing procedure is of particular importance in the case of the polymerization of olefins that are readily polymerized by acid catalysts, as for example, styrene, to avoid the production of the ordinary acid-catalyzed type of polymer in the process of this invention. The hydrocarbon-insoluble reaction product catalyst component prepared as described above may be used immediately in the polymerization process or it may be stored until such time as it is desired to use it. Many of the hydrocarbon-insoluble reaction products are highly pyrophoric when dry, but they are readily stored as a suspension in an inert hydrocarbon diluent. Usually they are stored at low temperatures such as C. or below, any further aging effects or other changes thereby being substantially minimized.

As has already been pointed out, the process in accordance with this invention involves the use of a two-component catalyst system, one of which is the hydrocarboninsoluble reaction product prepared as described above, and the other is an organometallic compound of a metal selected from the group of alkali metals, alkaline earth metals, zinc, earth metals, and rare earth metals, which compounds have already been exemplified above. This second catalyst component may be the same organometallic compound that was used in preparing the insoluble reaction product catalyst component or a different organometallic compound. Thus, when the polymerization is carried out in accordance with this invention, it is possible to use the less active but more readily prepared metal alkyls such as the aluminum sesquihalides for the preparation of the insoluble catalyst component and then in the polymerization process, use as the second catalyst component a metal alkyl such as triethylaluminum and still have one of the most active polymerization catalysts. Obviously this results in great overall economies. Particularly advantageous results are obtained in the process of this invention when the nonacidic metal alkyls or aryls, such as lithium alkyls or aryls, sodium alkyls or aryls, calcium alkyls, aluminum trialkyls or aryls, as for example, trimethylaluminum, triethylaluminum, triisobutylaluminum, trioctylaluminum, triphenylaluminum, etc., are used as the second catalyst component.

A very outstanding advantage in the use of the twocomponent catalyst combination used in this invention for the polymerization of olefins is that much lower catalyst concentrations may be used, and still obtain a practical rate, than when the transition metal compound and metal alkyl are merely mixed and used as such. As a result, the polymer so produced has a much lower inorganic content. The amount of each of the two catalyst components used in carrying out the polymerization in accordance with this invention will depend upon the monomer being polymerized, whether a batch or continuous process is used, whether they are mixed all at once, or in the bat-ch process, one or both are added in increments, or in the continuous process, one or both are continuously added. In general, the amount of the insoluble transition metal catalyst component will be within the range of from a minor catalytic amount to a large excess, as for example, from about 0.1 to about 1000 millimoles per mole of monomer and in the batch process may be from about 0.1 millimole per liter of reaction mixture to about millimoles per liter, and in some types of continuous operation even higher concentrations might be used. The amount of the organometallic catalyst component added will depend not only on the above variations but also on the activity of the organometallic compound being added. Usually the molar ratio of organometallic catalyst component to the insoluble transition metal catalyst component will be within the range of from about 0.05:1 to about 100:1, and preferably from about 0.2:1 to about 20:1.

Any ethylenically unsaturated hydrocarbon or mixtures thereof may be polymerized by the process of this invention, as for example, hydrocarbons containing vinylident, vinyl, or vinylene groups. The invention is of particular importance for the polymerization of monoethylenically unsaturated hydrocarbons wherein the unsaturated group is a vinylidene group, which compounds have the general formula where R is alkyl and R is alkyl, cycloalkyl, aralkyl, aryl, or alkaryl and those wherein the vinylidene group is a vinyl group, which compounds have the general formula CH CHR where R is hydrogen, a linear alkyl, a branched chain alkyl, cycloalkyl, aryl, aralkyl, or alkaryl, and for the polymerization of polyethylenically unsaturated hydrocarbons such as conjugated diolefins. Exemplary of the ethylenically unsaturated hydrocarbons which may be homopolymerized or mixtures of which may be copolymerized are the linear l-olefins such as ethylene,

propylene, butene-l, hexene-l, heptene-l, octene-l, octadecene-l, dodecene-l, etc., and branched chain l-olefins and other olefins such as isobutylene, cis-butene, diisobutylene, tert-butylethylene, 4- and S-methylheptenes-l, tetramethylethylene, and substituted derivatives thereof such as styrene, a-methylstyrene, vinylcyclohexane, diolefins such as hexadiene-l,4, 6-methylheptadiene-l,5 and conjugated diolefins such as butadiene, isoprene, pentadiene-1,3, cyclic olefins such as cyclopentadiene, cyclohexene, 4-vinylcyclohexene-l, terpenes such as ,B-pinene, etc. As has already been mentioned, the process of this invention makes it possible to polymerize even the more ditficultly polymerizable olefins under very mild conditions of temperature and pressure. In fact, by means of this invention it has been possible for the first time to polymerize propylene at atmospheric pressure.

The polymerization of the ethylenically unsaturated hydrocarbon or copolymerization of any mixture of two or more such compounds may be carried out in a wide variety of ways. The process may be carried out as either a batch or continuous operation and with or without the use of an inert organic diluent as the reaction mixture. With the more volatile monomers, a diluent is usually preferred. Any inert liquid organic solvent may be used, as for example, aliphatic hydrocarbons such as cyclohexane, aromatic hydrocarbons such as benzene, toluene, xylene, etc., or any mixture of such hydrocarbons, halogenated aromatic hydrocarbons such as chlorobenzenes, chloronaphthalenes, etc.

The selection of the temperature and pressure used for the polymerization process will obviously depend upon the monomer, the activity of the catalyst system being used, the degree of polymerization desired, etc. In general, the polymerization will be carried out at room temperature or slightly above, but any temperature within the range of from about 50 C. to about 150 C. and preferably from about C. to about 100 C. may be used. In the same way, while atmospheric pressure or a pressur of only a few pounds may be used, the polymerization may be carried out over a wide range of pressures, as for example, from a partial vacuum to about 1000 lbs. and preferably from about atmospheric to about 500 lbs. pressure. Higher pressures may, of course, be used, but generally do not appreciably alter the course of the polymerization.

The manner in which the two catalyst components are added to the polymerization system will depend upon the method by which the polymerization is carried out. They may be added all at once, in any order, or one or the other or both may be added in increments or continuously during the polymerization. Excellent results, and in some cases superior results, may be obtained by mixing the two catalyst components together, allowing the mixture to age for a short time and then adding the mixture all at one time, in increments, or continuously to the polymerization process. The two catalyst components that are combined for the polymerization will depend upon the monomer being polymerized, the degree of polymerization, etc. For the readily polymerized olefins such as ethylene, excellent results may be obtained with any combination of a hydrocarbon-insoluble component with organometallic catalyst component. For less readily polymerized olefins, the most active combinations are preferred, as for example, the hydrocarbon-insoluble reaction product, produced from titanium tetrachloride and an alkylaluminum halide, in combination with triethylor other trialkylaluminum as the second component.

The following examples will illustrate the polymerization of olefins in accordance with the process of this invention. The molecular weight of the polymers produced in these examples is shown by the Reduced Specific Viscosity (RSV) given for each. By the term Reduced Specific Viscosity is meant the nsp./ C. determined on a 0.1% solution of the polymer in decalin, containing 0.1 g. of the polymer per 100 ml. of solution, at 135 C. Where the melting point of the polymer is given, it is the temperature at which the birefringence due to crystallinity disappears. All parts and percentages are by weight unless otherwise indicated.

PREPARATION OF THE HYDROCARBON- INSOLUBLE CATALYST COMPONENT The preparation of the hydrocarbon-insoluble reaction product of titanium tetrachloride and diethylaluminum chloride used as one of the catalyst components in Examples 1-3 is typical of the preparation of these catalyst components and was carried out as follows:

A sealed vessel, from which the air had been evacuated and replaced by nitrogen, was charged with 32.6 parts of n-heptane, 14.3 parts of a 1.12 molar solution of diethylaluminum chloride in n-heptane, and 16.6 parts of a 0.5 molar solution of titanium tetrachloride in n-heptane (molar ratio of aluminum compound to titanium compound of 2:1). The mixture was stirred and then allowed to stand for 2 hours at room temperature. The reaction mixture was centrifuged, the supernatant liquid removed, and fresh n-heptane was added to bring it to the original volume. The insoluble precipitate was resuspended by agitation and the mixture was again centrifuged and the supernatant removed. After again adding nheptane to the original volume, the catalyst was aged for one day at room temperature and then stored at 15 C. until used for polymerization.

The hydrocarbon-insoluble reaction products of other transition or heavy metal compounds and organometallic compounds used in the other examples below were prepared in the same fashion but the reactants, molar ratio of reactants, etc., were varied as indicated in each case. Some of these suspensions of insoluble reaction product were used Without aging, others were aged for varying lengths of time and temperature. Such variations are also indicated in each case.

Examples 1-9 The air in a series of polymerization vessels was replaced with nitrogen and into each was then charged 33 parts of n-heptane and 8 parts of propylene after which the vessel was placed on a rotating rack in a constant temperature bath held at 30 C. When the vessel and contents were equalized at that temperature (an initial pressure of about 45 p.s.i.g.), the metal alkyl catalyst component was introduced and then the hydrocarbon-insoluble reaction product catalyst component was added, the former as a 1 M solution in n-heptane and the latter as a suspension in n-heptane prepared as described above. In Table I below are set forth, for each of these examples, the aluminum alkyl used to react with titanium tetrachloride in the preparation of the hydrocarbon-insoluble reaction product used as one component of the polymerization catalyst and the molor ratio of the two reactants used, the amount of this insoluble catalyst component added to the polymerization vessel, the metal alkyl used as the second catalyst component and the parts of it added to each polymerization vessel. In Examples 8 and 9 the insoluble catalyst component was aged, prior to separation and purification, at room temperature and the length of such aging is shown. In the remaining examples this catalyst component was used immediately after preparation and without aging. The reaction time shown in the table is taken from the time the hydrocarbon-insoluble catalyst component was added to the polymerization system.

At the end of the specified reaction time, the polymerization was stopped by the addition of 4 parts of anhydrous ethanol. Both heptane-soluble and heptane-insoluble polymers were produced. The insoluble polymer in each case was separated by filtration, washed twice with n-heptane, twice with absolute ethanol and then was refluxed for 15 minutes with 40 parts of 10% methanolic hydrogen chloride, after which it was washed acidfree with methanol and then dried for 4 hours at C. in vacuo. The heptane-soluble polymer was isolated by combining the reaction mixture filtrate and heptane washings, concentrating by distillation, and then precipitating the polymer by adding a large excess of anhydrous ene to polyethylene, Reduced Specific Viscosity, and melting point of the crystalline polymer are also tabulated in Table II.

ethanol. The polymer so obtained was washed with What I claim and desire to protect by Letters Patent ethanol and then dried for 16 hours at 80 C. in vacuo. 5 is:

The heptane-insoluble polypropylene produced in these 1. The method of preparing catalysts for olefin polymexamples is a crystalline material whereas the heptanemerization which comprises mixing a solution of an soluble polymer is rubbery. The amount of each proalkyl aluminum compound selected from the group conduced and their characteristics are shown in the table. In sisting of triethyl aluminum and diethylaluminum halide general, the insoluble polymer produced in these exam- 10 with a solution of titanium tetrachloride to form a slurry ples had a melting point of around 160 C. (162 C. in of a precipitate containing a reduced modification of Examples 1 and 3; 164 C. in Example 8; 168 C. in titanium tetrachloride and mixing said precipitate, whose Example 9). polymerization activity is reduced by storage prior to TABLE I Insoluble Reaction Product Catalyst Heptane-Soluble Heptane-Insol- Component Formed From Polymer uble Polymer Ex. Metal Alkyl Catalyst Parts Reaction No. Component X10-2 Time,

Parts 'IiCl A: Hrs. Percent Percent Al Alkyl X10? Fags Rat1o 1 Conv. RSV Conv. RSV

1 Al(C H Cl 12.06 9.5 2:1 A1 C2H5 3 11.4 0. 25 42 1.4 30 2.9 2 "do 0.03 4.75 211 do 11.4 2.0 30 1.8 60 3.9 3 d 0.03 4.75 2:1 Ale-mm... 19.8 2.0 47 2.2 as 4 0 4 t- Al(CzH5)3. 5. 7 4. 75 2:1 2H5)3 5. 7 19 46 0.5 7/8 4. 6 5 "do 5. 7 4. 75 2:1 AI(C2H5)2C1. 6. 0 10 0. 5 l5 5. 5 6 Al(CzH5)Cl2 12.7 4. 75 4-1 02115) 11.4 4.7 32 1.4 40 10.3 7 A1Sesquichloride 9.3 4.75 3:1 d0 11.4 3.5 35 2.2 47 4.8 8 Al(C( 1H5))Cl (Aged 12.7 475 411 .do 11.4 43 16 1.2 05 15.3

26 ays. 9 Al(CzH5)2Cl (Aged 1.5 4.75 0.5:1 undo 11.4 19 20 2.4 as 5.5

35 days).

1 Molar ratio of aluminum alkyl to titanium tetrachloride used in the preparation of the insoluble reaction product. 2 Added in two increments of 0.057 part each, the second added one hour after the first.

Examples 10-15 In this series of examples, each polymerization vessel (nitrogen atomsphere) was charged with 33 parts of nheptane, then evacuated and 2 parts of ethylene was added. After equalizing at C., a solution of the organometallic catalyst component in n-heptane and the suspension of the insoluble titanium catalyst component in n-heptane were added. The initial pressure was about 50 p.s.i.g. The aluminum alkyl, the ratio of aluminum alkyl to titanium tetrachloride and aging, if any, used in the preparation of the insoluble titanium catalyst component, the metal alkyl, and the parts of each catalyst component added to the polymerization system in each case are set forth in Table 11 below.

When the polymerization was substantially complete as indicated by a drop in the gage pressure to 0 p.s.i., 4 parts of anhydrous ethanol was introduced to stop the polymerization. The polymer which had separated as an insoluble precipitate in each case was separated by filtration, washed twice with n-heptane, twice with absolute ethanol, refluxed for 15 minutes with 40 parts of a 10% methanolic solution of hydrogtn chloride, filtered, and .the polymer was washed with methanol until the filtrate was acid-free. The polymers so obtained were then dried for 4 hours at 80 C. in vacuo. The conversion of ethylcontact with olefins, with an alkyl aluminum compound having a relatively low reducing activity, diflFering from said alkyl aluminum compound previously utilized and selected from the group consisting of ethyl aluminum dihalides, and dimethyl aluminum halides, to form a polymerization catalyst of increased activity.

2. The method of preparing catalysts for olefin polymerization which comprises mixing a solution of an alkyl aluminum compound selected from the group consisting of triethyl aluminum and diethyl aluminum halide with a solution of titanium tetrachloride to form a slurry of a precipitate containing a reduced modification of titaniumtetrachloride and mixing said precipitate, Whose polymerization activity is reduced by heating prior to contact with olefins, with an alkyl aluminum compound having a relatively low reducing activity, differing from said alkyl aluminum compound previously utilized and selected from the group consisting of ethyl aluminum dihalides and dimethyl aluminum halides, to form a polymerization catalyst of increased activity.

3. The method of preparing catalysts for olefin polymerization which comprises mixing a solution of an alkyl aluminum compound selected form the group consisting of triethyl aluminum and diethyl aluminum halide with a solution of titanium tetrachloride to form a slurry of TABLE II Insoluble Reaction Produiz t Catalyst Component Formed E r0m Organometallic Parts Reaction Time Percent Cryst. Catalyst 10- Hrs. Conv. RSV M.P. 0.

Parts TiCl A: T Component Al Alkyl XlO- Parts Ratio 1 Aged 2 6.03 4. 2:1 1 day"- A1(C2H5)C17 12.7 2.4 78 21,0 134 6.03 4. 75 2:1 do. Al(C2Hs)2Cl 6.03 1.0 13,4 132 6.03 4. 75 2:1 do A1(CzH5)4 5.7 0.25 (rn)1nus4 90 10.0 136 H 5.7 4.75 2:1 Al(C H5)Clz 12.7 19(14 p.s.i.) 05 54.9 136 %i 51 0 f 5.7 4.75 2:1 0 119401-. 0.03 0.2...- 04 27.4 136 151: do 5.7 475 2:1 14103 5.7 0.25 (1 11)1nus 7 92 12.1 139 1 Molar ratio of aluminum alkyl to titanium tetrachloride used in preparation of the insoluble reaction product. 1 Length of time this catalyst component was aged at room temperature mm to separation and punficatlon.

a Time to 0 gage pressure unless otherwise indicated.

a precipitate containing a reduced modification of titanium tetrachloride, separating the precipitate from the slurry, storing it and mixing said precipitate With an alkyl aluminum compound having a relatively low reducing activity, differing from said alkyl aluminum compound previously utilized and selected from the group consisting of ethyl aluminum dihalides, and dimethyl aluminum halides, to form a polymerization catalyst of increased activity.

No references cited.

5 TOBIAS E. LEVOW, Primary Examiner.

S. BLECH, J. G. LEVITT, Assistant Examiners. 

1. THE METHOD OF PREPARNG CATALYSTS FOR OLEFIN POLYMMERIZATION WHICH COMPRISES MIXING A SOLUTION OF AN ALKYL ALUMINUM COMPOUND SELECTED FROM THE GROUP CONSISTING OF TRIETHYL ALUMINUM AND DIETHYLALUMINUM HALIDE WITH A SOLUTION OF TITANIUM TETRACHLORIDE TO FORM A SLURRY OF A PRECIPITATE CONTAINING A REDUCED MODIFICATION OF TITANIUM TETRACHLORIDE AND MIXING SAID PRECIPITATE, WHOSE POLYMERIZATION ACTIVITY IS REDUCED BY STORAGE PRIOR TO CONTACY WITH OLEFINS, WITH AN ALKYL ALUMINUM COMPOND HAVING A RELATIVELY LOW REDUCING ACTIVITY, DIFFERING FROM SaID ALKYL ALUMINUM COMPOUND PREVIOUSLY UTILIZED AND SELECTED FROM THE GROUP CONSISTING OF ETHYLENE ALUMINUM HALIDES, AND DIMETHYL ALUMINUM HALIDE TO FORM A POLYMERIZATION CATALYST OF INCREASED ACTIVITY. 